How to shoot Infrared with a Sigma SD14

[Steaphany]

The infrared photography that I have done with my SD14 has been achieved with NO customizations or modifications performed on the camera. The only requirement is removal of the dust protector, a very fragile hot mirror mounted in a plastic frame which is snapped into the light path to minimize environmental dust from reaching the imager. The hot mirror is responsible for the reduction in infrared light allowing for the SD14 to achieve a normal color rendition for visible light photography.

When shooting, I typically use a IR720 filter, comparable to an 89B or B+W 092 dark red filter. Other filters that I have and yet to fully characterize are a 25A red and IR850 and IR950 black. Regardless of what infrared passing filter that you choose, you need to perform a reverse exposure compensation. This is because the SD14's meter appears to be very green sensitive and the Foveon imager is very infrared sensitive. An Infrared filter, which range from red to black, leaves no light for the meter to set an exposure. I have found that a proper infrared exposure can be -3EV to -6EV from what the meter specifies. Since the exposure compensation bottoms out at -3EV, I usually take a exposure reading and in manual drop the exposure to -3EV and follow this with additional exposures at -1EV steps to ensure that I'll get one right.

Another thing to keep in mind is some lenses can produce infrared hotspots, where the center of the frame is washed out with a unfocused bright area. This can be minimized or eliminated by ensuring that the aperture is not wide open. With my Sigma 28mm DG EX Aspherical Macro lens, I find that an f/4 or smaller is sufficient. An added benefit is the depth of field improves and focus becomes less critical.

What can take a bit to get use to is how infrared photos look right out of the SD14 - Like crap. There is no detail, everything is Magenta, even the focus looks poor. Here is an example:



That is what took me so long to get past. Getting RAW images looking like this can really make you wonder if you did something wrong. The key to SD14 infrared photography is post processing. In the example here, I did everything in Sigma's Photo Pro Version 3.5.2 software (SPP).

The SPP Adjustment window showing the histogram also points out some aspects of how the SD14 operates:



The histogram shows that the red channel starts midrange and saturates. The blue channel is completely in the midrange and there is no green. Even when shooting with no infrared passing filter, the intensity of the red channels seems to drain any signal on the green channel. Another factor that you need to get use it is the color histogram can not be used to judge exposure, which will become evident in the following examples.

To achieve a monochome image, instead of just lowering the color saturation, SPP Version 3.5.2 has a Monochrome option under the White Balance Setting. Switching from a Sunlight to Monochrome white balance produces:



and here you can see the resulting histogram:



As you can see, the histogram has everything within the midrage, nothing under or over exposed. Compare this to the prior histogram and you'll begin to understand the challenge. The image itself has clear focus and detail impossible to see from the Sunlight White balanced image. I am not familiar with what Sigma does behind the scenes within SPP to pull off such a drastic change with the same image file.

Since the contrast needs a bit of improvement, I made the following adjustments:



where I brightened the image, raised the contrast, darkened the shadows and lightened the highlights for this final image:



A suggestion for needing to quickly switch between infrared and natural light photography is to get an X-Nite CC1 color correction filter from LDP, LLC. The CC1 is a non-dichroic cyan colored filter which is used to attenuate infrared light for infrared converted cameras. When you switch from an infrared passing filter to the CC1, you gain the ability to easily switch shooting modes. The only problem with the CC1 over Sigma's dust protector/hot mirror is the CC1 leaves a cyan cast to the image which needs to be adjusted in post processing.

I have and tried using a Tiffen Hot Mirror and found that it is not sufficiently strong to return the SD14 to natural light operation. Additionally, the Tiffen hot mirror causes a significant difference between it's effect on the center versus the periphery of the image. Save your money and go with a CC1.

I still need to do work to achieve false color infrared and I'll post that how to at a later date.

[Steaphany]

For those who may not have found it yet, my thread on Nature & Architecture, where I originally posted my first successful infrared photos, has evolved into some nice technical content.

Please read "Finally figured out Infrared with my SD14"

[Melodasi]

Hi

I just bought a second hand sd14, but it came without the original, so I have downloaded the newest version 4 of photo pro, but I could not find the White balance settings at all. Any ideas?
One ore thing...did you use any ir filter for the picture above?

Marcelo

[Steaphany]

Yes, I used a IR720 filter, comparable to an 89B or B+W 092 dark red filter. For the latest Sigma Photo Pro, just go here:

http://www.sigma-sd.com/SD14/software/index.html

The White Balance settings are in the Adjustment Window below the Tonal Adjustment sliders and above the Color Mode, the Color Mode will be unavailable for the SD14:

See where is says "White Balance Setting" just use the pull down to select the White Balance. A word of warning, if you change the White Balance of a X3F file, the setting is made and saved to the disk without an option of being asked or for confirmation that you want to over write the original file. When I realized how this operates, I either avoid it or make a copy of the original file so I always have the as produced by the SD14 version to return to.

[ludoTW]

Hello,

It is after reading this thread started by Steaphany that I got my hand on a SD15 and an XDP IR filter from maxmax.com. Steaphany thank you for sharing your experiences, you got me into IR photography. But how come none of the images in your first thread appear in the text?
Have you began working on false colour IR?

Ludovic

[xpatUSA]

Hello,
. . . But how come none of the images in your first thread appear in the text?
Have you began working on false colour IR?
Ludovic

Ludovik, the thread started over 3 years ago - so the image links may no longer exist and you may not get a reply to your question.